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Monthly Archives for May, 2013

Avoid ditches

Posted on: May 14th, 2013 by

An infinite number of narrow parallel ditches \sqrt{2} meters apart have been dug out across a very long straight road. Prove that no matter how narrow these ditches are, a pedestrian with a step of length 1 meter inevitably steps into a ditch. via Moscow mathematical olympiad

Gambling with cards

Posted on: May 13th, 2013 by

Suppose you have a deck of cards. You have $1. You bet an amount x1 that the card dealt will be black (or red). After you see the card, you get paid x1 if you win and you lose x1 if you lose. Now you bet x2 that the next card will be black (or red, you get to pick). You win x2 if you Continue reading the story "Gambling with cards"

In the dark

Posted on: May 12th, 2013 by

A completely black dog was strolling down Main street during a total blackout affecting the entire town. Not a single streetlight had been on for hours. As the dog crosses the center of the road a Buick Skylark with 2 broken headlights speeds towards it, but manages to swerve out of the way just in time. How could the driver see the dog to swerve Continue reading the story "In the dark"

world's hardest easy Geometry problem

Posted on: May 11th, 2013 by

Find the angle x in the figure below: via here

What can Google not find?

Posted on: May 10th, 2013 by
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Write the smallest positive integer that returns 0 results on a Google search. You can use any programming language/api to find the answer. via Gajanana GK.

cutting a cake

Posted on: May 9th, 2013 by

How would you cut a rectangular cake into two equal pieces when a rectangular piece has already been cut out of it? The cut piece can be of any size and orientation. You are only allowed to make one straight cut. via Google interview puzzles

Draw poker

Posted on: May 8th, 2013 by

This puzzle is from Gardner's book "My Best Mathematical and Logic Puzzlez". You are playing poker with a friend, except that all the cards are shown face up. Here's how the game works: You first pick 5 cards (you can see all cards, so you can pick a royal flush if you want). Then your friend picks 5 cards (he can choose the cards he wants) Then you Continue reading the story "Draw poker"

Breaking record

Posted on: May 7th, 2013 by

You participate in the long jump event at olympics and break the world record. However, you don't win any prize for the event. Why? via cartalk.com

5 lines of 4 marbles

Posted on: May 6th, 2013 by

Arrange 10 marbles on a floor so that there are 5 lines of 4 marbles each. via Math factor

weight of a clerk

Posted on: May 5th, 2013 by
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A clerk at a butcher shop stands five feet ten inches tall and wears size 13 sneakers. What does he weigh? via Forbes

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